Le Tutoriel de Java ChronoUnit

public enum ChronoUnit implements TemporalUnit

public Duration getDuration()   

public boolean isDurationEstimated()  

public boolean isDateBased()  

public boolean isTimeBased()  

public boolean isSupportedBy(Temporal temporal)  

public <R extends Temporal> R addTo(R temporal, long amount)  

public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive)

LocalDateTime localDateTime1 = LocalDateTime.of(2020, 3, 15, 0, 30, 45);
LocalDateTime localDateTime2 = LocalDateTime.of(2020, 3, 17, 13, 30, 45);

Duration duration = Duration.between(localDateTime1, localDateTime2);
System.out.println("duration: " + duration); // PT61H (61 Hours)

long days = ChronoUnit.DAYS.between(localDateTime1, localDateTime2);
System.out.println("days: " + days); // 2

ZonedDateTime now = ZonedDateTime.now();
// Plus 2 days
ZonedDateTime after2Days = now.plus(2, ChronoUnit.DAYS);

System.out.println("Now is: " + now);
System.out.println("After 2 days: " + after2Days);

LocalDate isoDate = LocalDate.of(2020, 3, 15);
System.out.printf("isoDate: %s%n%n", isoDate); // 2020-03-15

JapaneseDate japaneseDate = JapaneseDate.from(isoDate);
JapaneseEra era = japaneseDate.getEra();

System.out.printf("japaneseDate: %s%n", japaneseDate); // Japanese Reiwa 2-03-15
System.out.printf(" > era: %s", era); // Reiwa

Duration maxDuration = ChronoUnit.FOREVER.getDuration();

for (final ChronoUnit unit : ChronoUnit.values()) {
    final Duration duration = unit.getDuration();
    System.out.println(unit + ": " + duration + " (" + duration.getSeconds() + " seconds)");
}

LocalDateTime localDateTime1 = LocalDateTime.of(2020, 3, 15, 9, 30, 45);
LocalDateTime truncatedLDT1 = localDateTime1.truncatedTo(ChronoUnit.HALF_DAYS);

System.out.printf("localDateTime1: %s%n", localDateTime1); // 2020-03-15T09:30:45
System.out.printf(" > truncated: %s%n%n", truncatedLDT1);  // 2020-03-15T00:00

LocalDateTime localDateTime2 = LocalDateTime.of(2020, 3, 15, 13, 30, 45);
LocalDateTime truncatedLDT2 = localDateTime2.truncatedTo(ChronoUnit.HALF_DAYS);

System.out.printf("localDateTime2: %s%n", localDateTime2); // 2020-03-15T13:30:45
System.out.printf(" > truncated: %s", truncatedLDT2);      // 2020-03-15T12:00

ZonedDateTime parisNow = ZonedDateTime.now(ZoneId.of("Europe/Paris"));
System.out.println("Now in Paris: " + parisNow);
  
ZonedDateTime parisNowHour = parisNow.truncatedTo(ChronoUnit.HOURS);
System.out.println("Truncated to Hour: " + parisNowHour);

public Duration getDuration()

Duration monthDuration = ChronoUnit.MONTHS.getDuration();  
// to days: 30 days
System.out.println("monthDuration.toDays(): " + monthDuration.toDays());  

// to hours: 730 hours ~ 30.41 days.
System.out.println("monthDuration.toHours(): " + monthDuration.toHours());

Period period = Period.of(1, 2, 15); // 1 year 2 months 15 days.

int years = period.getYears(); // 1
int months = period.getMonths(); // 2
int days = period.getDays(); // 15

System.out.println("years: " + years); // 1
System.out.println("months: " + months);// 2
System.out.println("days: " + days); // 15

Duration yearsDuration = ChronoUnit.YEARS.getDuration().multipliedBy(years);
Duration monthsDuration = ChronoUnit.MONTHS.getDuration().multipliedBy(months);
Duration daysDuration = ChronoUnit.DAYS.getDuration().multipliedBy(days);

Duration totalDuration = yearsDuration.plus(monthsDuration).plus(daysDuration);

long estimatedDays = totalDuration.toDays();
long estimatedHours = totalDuration.toHours();
System.out.println("Estimated days: " + estimatedDays); // 441 days
System.out.println("Estimated hours: " + estimatedHours); // 10586 hours ~ 441.08 days.

public boolean isDurationEstimated()

for (ChronoUnit unit : ChronoUnit.values()) {
    if (unit.isDurationEstimated()) {
        System.out.println(unit.name());
    }
}

public boolean isDateBased()

for (ChronoUnit unit : ChronoUnit.values()) {
    if (unit.isDateBased()) {
        System.out.println(unit.name());
    }
}

public boolean isTimeBased()

for (ChronoUnit unit : ChronoUnit.values()) {
    if (unit.isTimeBased()) {
        System.out.println(unit.name());
    }
}

public boolean isSupportedBy(Temporal temporal)

Temporal localDate = LocalDate.now();
System.out.println("Does LocalDate support: ");

for(ChronoUnit unit: ChronoUnit.values()) {
    System.out.println(unit.name() + "? " + unit.isSupportedBy(localDate));  
}

public <R extends Temporal> R addTo(R temporal, long amount)

// Defined in Temporal interface
public Temporal plus​(long amountToAdd, TemporalUnit unit)

Temporal ym = YearMonth.of(2020, 3); // 2020-03
// Add 10 monthds to ym.
YearMonth ym2 = (YearMonth) ChronoUnit.MONTHS.addTo(ym, 10);

System.out.println("ym2: " + ym2); // 2021-01

public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive)

// Defined in Temporal interface
public long until​(Temporal endExclusive, TemporalUnit unit)

LocalDate from = LocalDate.of(2020, 3, 15);
LocalDate to = LocalDate.of(2020, 3, 17);

long days = ChronoUnit.DAYS.between(from, to);
System.out.println("days: " + days); // 2

YearMonth from = YearMonth.of(2020, 7);
LocalDateTime to = LocalDateTime.of(2021, 3, 17, 13, 45, 30);

long months = ChronoUnit.MONTHS.between(from, to);
System.out.println("months: " + months); // 8